Gate for draw-bridges



G. A. JOHNSON.

GATE FOR DRAW BRIDGES.

(No Model.)

Photo-L'lhugmpllcr. Washington. D. c.

UNITED STATES I ATENT FFICEO GUSTAVE A. JOHNSON, OF OIHOAGO, ILLINOIS.

GATE FOR DRAW=BRIDGES.

SPECIFICATION forming part of Letters Patent No, 365,132, dated June 21,1887.

Application filed April I, 1857. Serial No. 211:3,51-2. .No model To allwhom, it may concern.

Be it known that I, GUs'L-WE A. J OIINSON, of Chicago, Illinois, haveinvented certain new and useful Improvements in Gates for Draw- Bridges,of which the following is a specification.

The invention relates to gates for drawbridges which are designed to beoperated automatically by the motion of the bridge; and the object of myimprovements is to provide a gate which is to be located above theroadway and to be let down by the opening of the bridge and raised upout of the way by the closing of the bridge.

I attain the object by the mechanism illustrated in the accompanyingdrawings, of which Figure l is a plan view. Fig. 2 is aside elevation.Fig. 3 is an enlarged longitudinal section of a detail. Fig. 4 is asection on line 00 w of Fig. 1. Fig. 5 is a crosssection on line 00 0cof Fig. 3, and Fig. 6 is an enlarged vertical section on line y y ofFig. 1.

A designates the gate, which may be of palings, bars, or lattice-work ofany ordinary con struction. The bars'or pales are connected to posts aor connected together in the gate in any ordinary way.

The particular form of the gate is not material, except that it suitablycloses the pits sage-way in the manner desired. Upon each side of theway or approach I erect a post, D, I as a guide and rest for the gate,and a box or i hollow post, B. These are connected at the top to aframe, 13 B".

O are upright posts carrying a windingshaft, 0, to which there areai'lixed two pulleys, D D, over each of which a chain or cord, (1,passes, to one end of which the gate is attached, and to the other end aweight, \V. The weights almost counterbalance the gate. They aresuspended in the hollow posts, and operate upon the gate at each endalike.

For the purpose of providing a safctyelutch for the gate, the guidepostsmay be provided with racks Z) in the bottom of the guideways and havethe chain attached to a pivoted arm, 2/,of the gate, arranged so thatthe part to which the chain is attached will drop down and cause theinner end, I), to engage the rack as a pawl and stop the gate fromfalling in case the chain should break. On the top of the frame 13 B Iplace a guide, E, provided with rollers e at the bottom and sides and agroove, 0, at the top. In this guide is a sliding bar, E, resting on therollers e at the bottom and just fitting between those at the sides, andhaving a tongue at the top fitting the groove 0. One end of the slidingbar is provided with a pulley, F, and to its other end is attached achain or cord, (1, which is also connected with a pulley, ii", fixed tothe shaft 0. The chain (1 is wound on the pulley (Z when the gate is letdown through the rotation of shalt G by the friction of the chains (1upon pulleys D D, the sliding bar being thereby extended or moved towardthe bridge G. The bridge is provided with an angular cam-rod, G, theangle g of which rests against the pulley F and holds the slid ing barin against the weight of the gate. As the bridge is drawn, the gatebeing slightly heavier than the weights gradually goes down until itrests its lower edge on the roadway. The pulleys D and d are soproportioned as to require only a slight extension of the sliding bar tolet the gate down and a slight movement back to raise the gate to aproper height above the roadway. As the bridge is closed, the outer endof the cam-rod comes in contact with the pulley F and slides the bar in.This unwinds the chain d, and so raises the gate. I prefer to make thecam rod straight between the central angle and the ends, though this isnot an essential feature. The gate being nearly balanced requires onlyslight pressure on the sliding bar to raise it.

The dotted lines at 1, Fig. 1, show the ex tent of movement ot' thesliding bar when the pulleys are proportioned as shown in the drawings.

\Vhat I claim is-- 1. The combination, with the gate A, pulleys l),cords (Z, and weights \V, of the sliding bar I l, pulley d", and cord(1, as and for the purpose specified.

2. The combination, with the gate A, pulleys D, cords (i, weights XV,and sliding bar 16, of the ln'idge provided with canned G, as and forthe purpose specified.

3. The combination, with a winding-shaft, as 0, weighted cords d,sliding bar E, and cord (1, of a draw-bridge provided with a cam-rod, G,as andfor the purpose specified.

G U ."TAVE A. JOHNSON. lVitnesscs:

JOHN II. WHIPPLE, J .uins It. DEAN.

